Since the emergence of the new coronavirus, we have come to understand it better than we initially did.
However, as research carries on, many grey areas and questions remain. For example, we weren’t sure whether this zoonotic virus – germs which are spread between animals and humans – could indeed spread from one human to another, until it was proven by scientists.
We also know that although the structure of the Covid-19 virus is similar to the virus that caused the SARS outbreak in 2003, the new coronavirus is much more contagious.
One of the most recent discoveries by genome experts is particularly interesting. They have found that the origin of the virus may be tracked back to two animal sources instead of one.
When we initially started talking about the new coronavirus, scientists thought it had come from a bat. In early February 2020 that theory was questioned when a virus even closer to the Covid-19 virus was discovered in a pangolin.
Experts did a genome report, which showed that the correspondence was a whopping 99%. But a more recent study shows that the genetic similarity between the Covid-19 virus and the virus found in the pangolin was actually less – which means that the pangolin cannot be wholly responsible for the current pandemic.
So, which species is responsible? According to researchers, the coronavirus isolated from the pangolin is actually 99% similar to a specific region of the S protein, which corresponds to certain amino acids in the so-called ACE2 receptors that help the virus to latch on to its human host cells.
The coronavirus that was isolated from the bat was in fact only 77% similar to the region explained above – which means that it is not so successful at entering human cells as the virus discovered in the pangolin.
The comparisons thus suggest that the viruses from the bat and the pangolin recombined. This combination is called a chimera (a single organism made up of two distinct genotypes).
What is important to know, is the fact that this newly created chimera has the capability to latch on to a whole different host – humans – and spread among the human population.
Although scientists are not 100% sure which exact species were involved or under what conditions the recombination took place, we are moving closer to understanding exactly where this new coronavirus came from, and where it might be heading to.
Image credit: CDC, Unsplash